Definition - What does Inner Room mean?
In fire safety contexts, an “inner room” is a room in which the only escape route from the room is through another room (called the “access room”).
This type of room is often considered a safety risk since a fire in the access room could trap individuals within the inner room. Inner rooms are also typically more difficult for fire fighting teams to access than rooms which directly adjoin a corridor or other area that leads to an exit/entry point.
The term is primarily used in United Kingdom regulatory contexts.
Safeopedia explains Inner Room
In some jurisdictions, the use of inner rooms is regulated according to building and fire codes. For instance, under the UK’s Regulatory Reform (Fire Safety) Order, it is not acceptable to place a bedroom at an above-ground level if that bedroom is also an inner room. In such instances, the bedroom must be equipped with a means of fire escape from a window that is sufficiently large for an adult to evacuate through.
In order to avoid noncompliance with applicable building codes, any design of an occupational space, such as an office, must account for regulations related to inner rooms. For example, the use of an inner room as an office may be acceptable if it adjoins an access room that has a fire exit; however, if that office were to be subdivided, it could potentially create an “inner inner room,” which would be deemed unacceptable.
An inner room is not necessarily allowed by a jurisdiction's building code even if the access room which it is attached to is equipped with a fire escape. The inner room itself must not have a capacity above 60 people (eliminating large conference rooms), and must be relatively close to the exit point in the access room. The inner room must also have visibility into the access room so that it is possible to see any workplace hazards that may occur there.